# Seesaw model with hidden $SU(2)_H \times U(1)_X$ gauge symmetry

## TL;DR

This paper introduces a novel seesaw model with a hidden $SU(2)_H imes U(1)_X$ gauge symmetry, organizing singlet fermions into doublets, and explores its implications for neutrino masses, lepton flavor violation, and collider phenomenology.

## Contribution

It formulates a new seesaw mechanism incorporating a hidden gauge symmetry and analyzes its effects on neutrino masses, lepton flavor violation, and collider signals.

## Key findings

- Z-Z' mixing constraints from the rho-parameter
- Potential Z' production at colliders via Z-Z' mixing
- Heavy neutrinos as dominant Z' decay products

## Abstract

We propose a seesaw model with a hidden gauge symmetry $SU(2)_H \times U(1)_X$ where two types of standard model singlet fermions in realizing a seesaw mechanism are organized into $SU(2)_H$ doublet. Then we formulate scalar and gauge sector, neutrino mass matrix and lepton flavor violations. In our gauge sector, $Z$-$Z'$ mixing appears after spontaneous symmetry breaking and we investigate constraint from $\rho$-parameter. In addition we discuss $Z'$ production at the large hadron collider via $Z$-$Z'$ mixing, where $Z'$ tends to dominantly decay into heavy neutrinos.